Absorption refrigeration



Patented May 19, 1936 2,040,902

UNITED STATES PATENT OFFICE ABSORPTION REFRIGERATION Glenn F. Zellhoefer, Bloomington, Ill.

No Drawing. Application April 18, 1935, Serial No. 17,065

- Claims.- (Cl. 2525) The present invention relates generally to a The particular characteristics of such a masolvent material and a refrigerant mixture for chine are that the still operates at temperatures absorption refrigerating machines, both of the well above normal temperatures, such, for extwo-fiuid type and of the three-fluid type. ample, at 210 F. to 250 F.; and that the cooling In absorption refrigeration there is required a unit operates at temperatures lower than normal, solvent material adapted to remain liquid such as from 15 F. to 50 F. Various parts of throughout the operation of the apparatus, and the apparatus differ in the prevailing temperaa refrigerant material adapted to have a liquid tures and pressures, and both pressure and temand a vapor phase in the cycles of operation, perature determine the physical state of the free adapted to be dissolved or absorbed in the solrefrigerant material, whether gaseous or liquid, vent, adapted to be evaporated or boiled as a and determine the solubility relations between vapor from the solvent mixture and from the the refrigerant and the solvent material. It is, solvent, and adapted to be condensed from the therefore, very important that the solvent and vapor to a liquid. Numerous refrigerants and the refrigerant materials be physically adapted numerous solvents are known, as well as successfor use as individual materials in certain places ful combinations of these. and for certain functions, and that they be mutu- The two-fluid absorption machines have cerally adapted for certain functions when they are tain mechanical parts which may be omitted or in combination. Other qualities not essential to which are not duplicated in three-fluid machines. refrigeration, but pertinent to practical usage,

In a three-fluid machine, there is in addition to control or limit the choice of solvent or refrigthe two-fluid mixture a body of inert gas which is erant, such as odor, viscosity, heat capacity, boilalways gas, and which does not to any substanng po nt, f e ng p Volatility, Chemical tial extent dissolve in any of the components of bility, reactivity, corrosive action, infiammability, the two-fluid composition, or in mixtures thereof. toxicity, etc.

The present invention is directed to a new 501- By considering the limitations herein set forth vent for absorption refrigeration, and to combiand suggested, I have been able to utilize tetranations thereof with refrigerants. hydrofurfuryl methoxyacetate as a solvent, for

A particular object of the invention is the use prac usage, in Combination t t refr of tetrahydrofurfuryl methoxyacetate as a solerant dichloromonofiuoromethane, which is little vent. known. Another object is the use of a combination of The new solvent is herein named as tetrahydr0 said solvent with the refrigerant dichloromonofurfuryl methoxyacetate. In order to leave no fluoromethane. doubt as to its identity, its structural formula is Examples of the two-fluid apparatus in which herein given:

the new solvent mateiial and the new combina- (C 413,10) CHzOCOCHzOCH3 5 tion may be used is disclosed in my co-pending application Serial No. 651,306, filed January 12, The refrigerant h n p fi is dichloro- 1933, or in my U. S. Patent No. 1,895,698, issued monofiuoromethane. In order to leave no doubt January 3- Other examples may readily as to its identity, its structural formula is herein be cited, and will be known to those skilled in given: 40 the art. CHClzF The two-fluid apparatus above referred to, In the accompanying claims the invention is briefly described, comprises a still in which a set forth as a combination useful in absorption liquid mixture of solvent and refrigerant is refrigeration. It is to be understood that a simheated to distill away as a vapor the refrigerant ple adulteration of the new solvent in its pure material, a condenser wherein said vapor is conform, either by reason of commercial impurities, densed to a liquid state, an evaporator wherein or by addition of lesser quantities of other mathe resulting liquid is vaporized at reduced presterial, useful also as solvent, is permitted, and sure to produce refrigeration, and an absorber such a composition is intended to fall within the in which vapor of the refrigerant material 0011- scope of the present invention.

tainingadded heat units (acquired in the refrig- An extended study has been made of the soluerating process) is again dissolved in the solvent bility of halogenated derivatives of methane and material. Suitable heat exchanging and circuethane in the ether and ester derivatives of tetralating means are included, and automatic conhydrofurfuryl alcohol, involving eleven individual trols may be provided. representative derivatives. The refrigerants I studied in conjunction with this group of sol- I by a relatively difluoromethane vents are: dichloromonofluoromethane (CHCIaF) trichloromonofluoromethane (CClaF) dichloro- (CCl F'i); methyl chloride (CH3C1); ethyl chloride (Cal-RC1). From this study it has been determined that the solubility characteristics of one halogenated derivative of methane 'or ethane cannot be used to predict the solubility characteristics of a different halogenated derivative of methane or ethane.

y with respect to the solubility characteristics of dichloromonofluoromethane in these derivatives, the-following observations may be made;

Derivatives of tetrahydrofurfuryl alcohol in which the hydroxyl hydrogen has been replaced short carbon chain acyL alkyl or alkoxy-acyl radical are good solvents for dichlorofluoromethane in refrigerant mixtures.

Where the acyl, alkyl or alkoxy-acyl radical consists of a relatively long carbon .chain in a derivative of tetrahydrofurfuryl alcohol, the

boiling point is raised but the solubility of dichloromonofluoromethane in the product is less than a corresponding derivative in which the acyl, alkyl, or alkoxy-aeyl radical consists of a shorter carbon'chain. f

Aromatic ether or ester. derivatives of tetrahydrofurfuryl alcohol are suitable but less satisfactory solvents for diehloromonofluoromethane in refrigerant mixtures than a corresponding derivative in which a short carbon chain acyl, alkyl, or alkoxy-acyl radical is used.

In'.(C4H1O) CHaR, where R is OCHa,v OCzHs, OCOCHa, OCOCHzOCHa, or OCOCHzOCzI-Is, the compounds are good solvents for dichloromonofluoromethane. in refrigerant mixtures.

It may be predicted as a Y result of said extended study, that in any of the above indicated series of compounds where R is OCHi, the product will be the better solvent for dichloromonofiuorormethane, than when R is OCzHs; these com- 7 pounds better than where R is OCOCHa; these compounds better than where R is OCOCHzOCHa these compounds better than where R is OCOCHaOCzHs. It may also be predicted as a result of said extended study, that in any one of the above indicated series of compounds where- R is OCHa, the product will have a lower boiling point than where R is OCaHs; these com- .OCHs,

1. A refrigerant mixture for the absorption type of refrigeration apparatus consisting of tetrahydrofurfuryl methoxyacetate as the essentially predominant solvent, and dichloromono- .fluoromethane as a refrigerant. i

2. A refrigerant mixture for the absorption type of refrigeration apparatus consisting of a dichloromonofluoromethane as a solute, and a the essentially predominant solvent, where R may be selected from the' group consisting of: OCHa, OCzHs, OCOCHa, OCOCHzOCHs, and OCOCI-IzOCzHs. 5

3. A refrigerant mixture for the absorption type of refrigeration apparatus consisting of tetrahydrofurfuryl methoxyacetate as the essentially predominant solvent, and a volatile chemically stable halogenated hydrocarbon refrigerant soluble in said solvent.

4. A refrigerant mixture for the absorption type of refrigeration apparatus consisting of a volatile chemically stable halogenated hydrocarbon refrigerant as a solute, and a solvent therefor consisting of (C4H7O) CHzR as the solvent therefor consisting of (C4H1O) CHzR as essentially predominant solvent, where R may i be selected from the group consisting of: OC2H5, OCOCHa, OCOCI-IzOCI-Ia, and OCOClI-IzOCzHs.

5. A refrigerant mixture for the absorption type of refrigeration apparatus consisting of a volatile chemically stable halogenated hydrocarbon refrigerant as a solute, and a solvent therefor consisting of a derivative of tetrahydrofuriuryl alcohol as the essentially predominant solvent, wherein the hydroxyl hydrogen has been replaced by an etheror ester-forming group. I

GLENN F. ZELLHOEFER. 

